Filovirus Emergence unit

Status: active - level 1

Last updated on 28 March 2025

Filovirus : l’essentiel de la situation

The Filoviridae family comprises single-stranded RNA viruses responsible for severe acute hemorrhagic fevers with high lethality, including Marburg virus disease (MVD) and Ebola virus disease (EVD). EVD is caused by viruses of the Orthoebolavirus genus, which includes Bundibugyo virus, Sudan virus, Taï Forest virus, Reston virus, and Zaire ebolavirus. The case fatality rate varies between 25% and 90%, depending on the outbreak.
On January 14, 2025, an outbreak of Marburg virus disease was declared in Tanzania, with 10 reported cases (2 confirmed, 8 probable) and a case fatality rate of 100%. After 42 consecutive days without new cases, the Ministry of Health officially declared the end of the outbreak on March 13, 2025.
On January 30, 2025, Uganda reported an outbreak of Sudan virus disease (SVD), with 14 cases (12 confirmed, 2 probable) and a case fatality rate of 29%. In response, an emergency vaccine trial (TOKOMEZA SVD) was initiated to assess the efficacy of the rVSV-SUDV vaccine among contacts of confirmed cases.

Stay updated on filovirus scientific developments

As part of the ANRS MIE Emergence programme and the CORC Filovirus program, the agency publishes a weekly scientific review on filoviruses, with a particular focus on Sudan virus—responsible for Ebola virus disease—and Marburg virus, providing updates on the most recent research findings.

In particular, you will find in the scientific review available for download:

a summary of the epidemiological situation ;
recent scientific articles published in peer-reviewed scientific journals;
recent articles and press releases;
official recommendations from health agencies ;
a brief overview of epidemiology, virology, clinical aspects, treatment and prevention

Download the scientific review

Monthly scientific review of filovirus .pdf 353 KB

Epidemiological situation of filoviruses

Ebola Virus Outbreaks

Since the first emergence of Ebola in 1976, with simultaneous outbreaks in South Sudan and the Democratic Republic of the Congo, a total of 42 Ebola outbreaks have been reported in Africa. Among them, 31 were caused by Ebola virus (EBOV)—also known as Zaire ebolavirus—resulting in 23,045 cases and 14,885 deaths (CFR 65%). Additionally, 8 outbreaks were attributed to Sudan virus (SUDV), with 956 cases and 503 deaths (CFR 53%).

The sporadic nature of these outbreaks suggests a probable zoonotic origin, although human-to-human transmission has been well documented.²

Marburg virus in Tanzania

On January 14, 2025, a Marburg virus (MARV) outbreak was reported in the Kagera region of Tanzania, with 8 deaths among 9 reported cases. By February 14, 2025, Tanzania reported a tenth case (2 confirmed, 8 probable), bringing the total to 10 deaths (CFR 100%).
On March 13, 2025, the Ministry of Health of the United Republic of Tanzania declared the official end of the Marburg virus disease (MVD) outbreak. This declaration followed two consecutive incubation periods (42 days in total) with no new detected cases since the last reported case.
This outbreak occurred only one month after the WHO declared the end of an MVD outbreak in Rwanda, which lasted three months and resulted in 15 deaths.⁵ Additionally, in March 2023, Tanzania had already reported its first Marburg outbreak in the Kagera region, with a total of 9 cases.

Sudan virus in Uganda

On January 30, 2025, the Minister of Health of Uganda declared an outbreak of Sudan virus disease (SVD) following the confirmation of a case in Kampala. By March 5, 2025, an additional 12 confirmed cases and 2 probable cases were reported, bringing the total to 14 cases across 6 districts (Figure 2), with 4 deaths (CFR 29%). Among these 14 cases, 8 patients have recovered since the outbreak began.
Following the latest confirmed cases, 192 high-risk contacts were identified and placed under active surveillance, in addition to the 308 previously identified contacts.⁶
In response to this outbreak, and with the support of the WHO, the Uganda Virus Research Institute (UVRI) launched a randomized vaccine trial—TOKOMEZA SVD—within four days. The trial evaluates the candidate vaccine rVSV-SUDV, with vaccination offered to identified contacts. This is the first outbreak-period trial assessing the clinical efficacy and immunogenicity of a single-dose vaccine against SUDV.⁶

WHO and ANRS MIE actions on filoviruses

Scientific Coordination: In 2024, ANRS MIE implemented a coordinated initiative on viral hemorrhagic fevers, chaired by Sylvain Baize, Marie Jaspard, and Abdoulaye Touré. This strategic group focuses particularly on scientific research related to filoviruses. Through its dedicated working groups (therapeutics, wildlife, vaccines), it aims to foster the emergence of research projects within the framework of international collaborations, primarily with partners in Africa.
Filovirus CORC: As part of its long-term commitment with WHO, the coordination of the Filovirus CORC has been entrusted to ANRS MIE. The CORCs are international networks of research institutions with the mission of strengthening global pandemic preparedness through collaborative research, knowledge sharing, and the rapid development of countermeasures. ANRS MIE, WHO, and all experts from the Filovirus CORC are currently engaged in revising research and surveillance priorities for filoviruses (WHO-AFIRM).